Soil Types in Kerala

Laterite is the predominant soil type found in Kerala. Other soil types—such as coastal soil, alluvial soil, black soil, red soil, hill soil, heavy cotton soil, and forest soil—are also found in various regions of the state. Coastal soil is found along Kerala's western coast and in its plains. This yellowish-brown soil has low fertility and poor moisture-retention capacity; however, coconut palms thrive in it. Hill soil is highly fertile; this brown soil extends to great depths. The forest soil found in Kerala's forest regions is also brown in color. Crops like sugarcane and paddy grow well in the black cotton soil found in the Palakkad region. Kerala's first soil museum was established in 2014 at Parottukonam in Thiruvananthapuram district. The museum operates in conjunction with the Central Soil Analytical Laboratory and displays 82 soil types found in Kerala.

There are ten major soil groups in kerala. They are Red soil, Laterite soil, Coastal alluvial soil, Riverine alluvial soil, Brown hydromorphic soil, Hydromorphic saline soil, Acidic salitic soil (Kuttanad Alliuvium), Black soil, Forest soil and Greyish Onattukara soil.

1. Red soil: The red colour of soil is due to the presence of Iron Oxide. It is mainly located in southern regions of Trivandrum. The soil is almost homogeneous. The acidity of the soil ranges from 4.8 to 5.9. The red soil is low in essential nutrients and organic matter.

2. Laterite soil: It is seen in districts of Kozhikode and Kannur. Majority of area comprises this type of soil. Heavy rainfall and high temperature are conducive for laterisation. Laterite soil covers an area of about 68% of the total area of the state. Laterites are poor in Nitrogen and Phosphorus. The water holding capacity of the soil is very low.

3. Coastal alluvial soil : It is seen in the coastal regions along the west. They have been developed from recent marine deposits. Permeability of the soil is more. The soil has low organic matter.

4. Riverine alluvial soil: It is seen in the coasts of rivers. The soil has moderate Organic Matter, Nitrogen and Potassium. It is mainly found in Kollam and Alappuzha districts.

5. Brown hydromorphic soil: It is found in river valleys. It Exhibits wide variation in physico - chemical and morphological properties. The main disadvantage of the soil is the drainage. The soil is rich in organic matter, Nitrogen and Pottasium. It is poor in lime.

6. Hydromorphic saline soil: It is common in the coastal zone of the districts Ernakulam, Kannur and Trichur. In the rainy season the fields are flooded resulting in losing the salt in soil. Huge amount of salts will sedimented during summer.

7. Acidic salitic soil (Kuttanad Alliuvium): It is found in the Kuttanad area that spreaded about 875 square km. The main disadvantage of the soil is salinity, flood and acidity. They can be grouped into three categories, the Kayal soils, the Karappadam soils and the Kari soils.

a. Kayal Soil - It comprises reclaimed areas of Kottayam and Alappuzha districts. Slightly acidic. Medium in organic matter content, poor in available nutrients but rich in Calcium.

b. Karappadam - Distributed over a large area of upper Kuttanad. River borne alluvial soil 1-2 m below the sea level. Generally clay loam in texture, high acidity, fair amount of organic matter, poor in available nutrients particularly Phosphorous. The soil is deficient in lime.

c. Kari Soil - The soil is acidic due to the presence of different forms of Sulphur. Kari soil resemble Peat soil.

8. Black soil: It is found in the region of Chittur in Palakkad district. The soil is low in organic matter, calcareous, moderately alkaline and high in clay content. It is medium in Phosphorous and Potassium content and low in Nitrogen.

9. Forest soil: It is formed by the weathering of crystalline rocks in the forest cover. The soil is high in organic carbon and also it is acidic. It is rich in Nitrogen and poor in Phosphorous.

10. Greyish Onattukara soil: It is the sandy soil found only in the Onattukara region. These soils are rare and available only in the Onattukara region including the places of Karunagapally (Kollam) and in the Karthikappally and Mavelikara taluks of Alappuzha.